<?php

/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2013 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPExcel
 * @package	PHPExcel_Writer_HTML
 * @copyright  Copyright (c) 2006 - 2013 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license	http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt	LGPL
 * @version	1.7.9, 2013-06-02
 */

/**
 * PHPExcel_Writer_HTML
 *
 * @category   PHPExcel
 * @package	PHPExcel_Writer_HTML
 * @copyright  Copyright (c) 2006 - 2013 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_Writer_HTML extends PHPExcel_Writer_Abstract implements PHPExcel_Writer_IWriter
{

    /**
     * PHPExcel object
     *
     * @var PHPExcel
     */
    protected $_phpExcel;

    /**
     * Sheet index to write
     *
     * @var int
     */
    private $_sheetIndex = 0;

    /**
     * Images root
     *
     * @var string
     */
    private $_imagesRoot = '.';

    /**
     * embed images, or link to images
     *
     * @var boolean
     */
    private $_embedImages = FALSE;

    /**
     * Use inline CSS?
     *
     * @var boolean
     */
    private $_useInlineCss = false;

    /**
     * Array of CSS styles
     *
     * @var array
     */
    private $_cssStyles = null;

    /**
     * Array of column widths in points
     *
     * @var array
     */
    private $_columnWidths = null;

    /**
     * Default font
     *
     * @var PHPExcel_Style_Font
     */
    private $_defaultFont;

    /**
     * Flag whether spans have been calculated
     *
     * @var boolean
     */
    private $_spansAreCalculated = false;

    /**
     * Excel cells that should not be written as HTML cells
     *
     * @var array
     */
    private $_isSpannedCell = array();

    /**
     * Excel cells that are upper-left corner in a cell merge
     *
     * @var array
     */
    private $_isBaseCell = array();

    /**
     * Excel rows that should not be written as HTML rows
     *
     * @var array
     */
    private $_isSpannedRow = array();

    /**
     * Is the current writer creating PDF?
     *
     * @var boolean
     */
    protected $_isPdf = false;

    /**
     * Generate the Navigation block
     *
     * @var boolean
     */
    private $_generateSheetNavigationBlock = true;

    /**
     * Create a new PHPExcel_Writer_HTML
     *
     * @param	PHPExcel	$phpExcel	PHPExcel object
     */
    public function __construct(PHPExcel $phpExcel)
    {
        $this->_phpExcel    = $phpExcel;
        $this->_defaultFont = $this->_phpExcel->getDefaultStyle()->getFont();
    }

    /**
     * Save PHPExcel to file
     *
     * @param	string		$pFilename
     * @throws	PHPExcel_Writer_Exception
     */
    public function save($pFilename = null)
    {
        // garbage collect
        $this->_phpExcel->garbageCollect();

        $saveDebugLog        = PHPExcel_Calculation::getInstance($this->_phpExcel)->getDebugLog()->getWriteDebugLog();
        PHPExcel_Calculation::getInstance($this->_phpExcel)->getDebugLog()->setWriteDebugLog(FALSE);
        $saveArrayReturnType = PHPExcel_Calculation::getArrayReturnType();
        PHPExcel_Calculation::setArrayReturnType(PHPExcel_Calculation::RETURN_ARRAY_AS_VALUE);

        // Build CSS
        $this->buildCSS(!$this->_useInlineCss);

        // Open file
        $fileHandle = fopen($pFilename, 'wb+');
        if ($fileHandle === false)
        {
            throw new PHPExcel_Writer_Exception("Could not open file $pFilename for writing.");
        }

        // Write headers
        fwrite($fileHandle, $this->generateHTMLHeader(!$this->_useInlineCss));

        // Write navigation (tabs)
        if ((!$this->_isPdf) && ($this->_generateSheetNavigationBlock))
        {
            fwrite($fileHandle, $this->generateNavigation());
        }

        // Write data
        fwrite($fileHandle, $this->generateSheetData());

        // Write footer
        fwrite($fileHandle, $this->generateHTMLFooter());

        // Close file
        fclose($fileHandle);

        PHPExcel_Calculation::setArrayReturnType($saveArrayReturnType);
        PHPExcel_Calculation::getInstance($this->_phpExcel)->getDebugLog()->setWriteDebugLog($saveDebugLog);
    }

    /**
     * Map VAlign
     *
     * @param	string		$vAlign		Vertical alignment
     * @return string
     */
    private function _mapVAlign($vAlign)
    {
        switch ($vAlign)
        {
            case PHPExcel_Style_Alignment::VERTICAL_BOTTOM: return 'bottom';
            case PHPExcel_Style_Alignment::VERTICAL_TOP: return 'top';
            case PHPExcel_Style_Alignment::VERTICAL_CENTER:
            case PHPExcel_Style_Alignment::VERTICAL_JUSTIFY: return 'middle';
            default: return 'baseline';
        }
    }

    /**
     * Map HAlign
     *
     * @param	string		$hAlign		Horizontal alignment
     * @return string|false
     */
    private function _mapHAlign($hAlign)
    {
        switch ($hAlign)
        {
            case PHPExcel_Style_Alignment::HORIZONTAL_GENERAL: return false;
            case PHPExcel_Style_Alignment::HORIZONTAL_LEFT: return 'left';
            case PHPExcel_Style_Alignment::HORIZONTAL_RIGHT: return 'right';
            case PHPExcel_Style_Alignment::HORIZONTAL_CENTER:
            case PHPExcel_Style_Alignment::HORIZONTAL_CENTER_CONTINUOUS: return 'center';
            case PHPExcel_Style_Alignment::HORIZONTAL_JUSTIFY: return 'justify';
            default: return false;
        }
    }

    /**
     * Map border style
     *
     * @param	int		$borderStyle		Sheet index
     * @return	string
     */
    private function _mapBorderStyle($borderStyle)
    {
        switch ($borderStyle)
        {
            case PHPExcel_Style_Border::BORDER_NONE: return 'none';
            case PHPExcel_Style_Border::BORDER_DASHDOT: return '1px dashed';
            case PHPExcel_Style_Border::BORDER_DASHDOTDOT: return '1px dotted';
            case PHPExcel_Style_Border::BORDER_DASHED: return '1px dashed';
            case PHPExcel_Style_Border::BORDER_DOTTED: return '1px dotted';
            case PHPExcel_Style_Border::BORDER_DOUBLE: return '3px double';
            case PHPExcel_Style_Border::BORDER_HAIR: return '1px solid';
            case PHPExcel_Style_Border::BORDER_MEDIUM: return '2px solid';
            case PHPExcel_Style_Border::BORDER_MEDIUMDASHDOT: return '2px dashed';
            case PHPExcel_Style_Border::BORDER_MEDIUMDASHDOTDOT: return '2px dotted';
            case PHPExcel_Style_Border::BORDER_MEDIUMDASHED: return '2px dashed';
            case PHPExcel_Style_Border::BORDER_SLANTDASHDOT: return '2px dashed';
            case PHPExcel_Style_Border::BORDER_THICK: return '3px solid';
            case PHPExcel_Style_Border::BORDER_THIN: return '1px solid';
            default: return '1px solid'; // map others to thin
        }
    }

    /**
     * Get sheet index
     *
     * @return int
     */
    public function getSheetIndex()
    {
        return $this->_sheetIndex;
    }

    /**
     * Set sheet index
     *
     * @param	int		$pValue		Sheet index
     * @return PHPExcel_Writer_HTML
     */
    public function setSheetIndex($pValue = 0)
    {
        $this->_sheetIndex = $pValue;
        return $this;
    }

    /**
     * Get sheet index
     *
     * @return boolean
     */
    public function getGenerateSheetNavigationBlock()
    {
        return $this->_generateSheetNavigationBlock;
    }

    /**
     * Set sheet index
     *
     * @param	boolean		$pValue		Flag indicating whether the sheet navigation block should be generated or not
     * @return PHPExcel_Writer_HTML
     */
    public function setGenerateSheetNavigationBlock($pValue = true)
    {
        $this->_generateSheetNavigationBlock = (bool) $pValue;
        return $this;
    }

    /**
     * Write all sheets (resets sheetIndex to NULL)
     */
    public function writeAllSheets()
    {
        $this->_sheetIndex = null;
        return $this;
    }

    /**
     * Generate HTML header
     *
     * @param	boolean		$pIncludeStyles		Include styles?
     * @return	string
     * @throws PHPExcel_Writer_Exception
     */
    public function generateHTMLHeader($pIncludeStyles = false)
    {
        // PHPExcel object known?
        if (is_null($this->_phpExcel))
        {
            throw new PHPExcel_Writer_Exception('Internal PHPExcel object not set to an instance of an object.');
        }

        // Construct HTML
        $properties = $this->_phpExcel->getProperties();
        $html       = '<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">' . PHP_EOL;
        $html .= '<!-- Generated by PHPExcel - http://www.phpexcel.net -->' . PHP_EOL;
        $html .= '<html>' . PHP_EOL;
        $html .= '  <head>' . PHP_EOL;
        $html .= '	  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">' . PHP_EOL;
        if ($properties->getTitle() > '')
            $html .= '	  <title>' . htmlspecialchars($properties->getTitle()) . '</title>' . PHP_EOL;

        if ($properties->getCreator() > '')
            $html .= '	  <meta name="author" content="' . htmlspecialchars($properties->getCreator()) . '" />' . PHP_EOL;
        if ($properties->getTitle() > '')
            $html .= '	  <meta name="title" content="' . htmlspecialchars($properties->getTitle()) . '" />' . PHP_EOL;
        if ($properties->getDescription() > '')
            $html .= '	  <meta name="description" content="' . htmlspecialchars($properties->getDescription()) . '" />' . PHP_EOL;
        if ($properties->getSubject() > '')
            $html .= '	  <meta name="subject" content="' . htmlspecialchars($properties->getSubject()) . '" />' . PHP_EOL;
        if ($properties->getKeywords() > '')
            $html .= '	  <meta name="keywords" content="' . htmlspecialchars($properties->getKeywords()) . '" />' . PHP_EOL;
        if ($properties->getCategory() > '')
            $html .= '	  <meta name="category" content="' . htmlspecialchars($properties->getCategory()) . '" />' . PHP_EOL;
        if ($properties->getCompany() > '')
            $html .= '	  <meta name="company" content="' . htmlspecialchars($properties->getCompany()) . '" />' . PHP_EOL;
        if ($properties->getManager() > '')
            $html .= '	  <meta name="manager" content="' . htmlspecialchars($properties->getManager()) . '" />' . PHP_EOL;

        if ($pIncludeStyles)
        {
            $html .= $this->generateStyles(true);
        }

        $html .= '  </head>' . PHP_EOL;
        $html .= '' . PHP_EOL;
        $html .= '  <body>' . PHP_EOL;

        // Return
        return $html;
    }

    /**
     * Generate sheet data
     *
     * @return	string
     * @throws PHPExcel_Writer_Exception
     */
    public function generateSheetData()
    {
        // PHPExcel object known?
        if (is_null($this->_phpExcel))
        {
            throw new PHPExcel_Writer_Exception('Internal PHPExcel object not set to an instance of an object.');
        }

        // Ensure that Spans have been calculated?
        if (!$this->_spansAreCalculated)
        {
            $this->_calculateSpans();
        }

        // Fetch sheets
        $sheets = array();
        if (is_null($this->_sheetIndex))
        {
            $sheets = $this->_phpExcel->getAllSheets();
        }
        else
        {
            $sheets[] = $this->_phpExcel->getSheet($this->_sheetIndex);
        }

        // Construct HTML
        $html = '';

        // Loop all sheets
        $sheetId = 0;
        foreach ($sheets as $sheet)
        {
            // Write table header
            $html .= $this->_generateTableHeader($sheet);

            // Get worksheet dimension
            $dimension       = explode(':', $sheet->calculateWorksheetDimension());
            $dimension[0]    = PHPExcel_Cell::coordinateFromString($dimension[0]);
            $dimension[0][0] = PHPExcel_Cell::columnIndexFromString($dimension[0][0]) - 1;
            $dimension[1]    = PHPExcel_Cell::coordinateFromString($dimension[1]);
            $dimension[1][0] = PHPExcel_Cell::columnIndexFromString($dimension[1][0]) - 1;

            // row min,max
            $rowMin = $dimension[0][1];
            $rowMax = $dimension[1][1];

            // calculate start of <tbody>, <thead>
            $tbodyStart = $rowMin;
            $theadStart = $theadEnd   = 0; // default: no <thead>	no </thead>
            if ($sheet->getPageSetup()->isRowsToRepeatAtTopSet())
            {
                $rowsToRepeatAtTop = $sheet->getPageSetup()->getRowsToRepeatAtTop();

                // we can only support repeating rows that start at top row
                if ($rowsToRepeatAtTop[0] == 1)
                {
                    $theadStart = $rowsToRepeatAtTop[0];
                    $theadEnd   = $rowsToRepeatAtTop[1];
                    $tbodyStart = $rowsToRepeatAtTop[1] + 1;
                }
            }

            // Loop through cells
            $row = $rowMin - 1;
            while ($row++ < $rowMax)
            {
                // <thead> ?
                if ($row == $theadStart)
                {
                    $html .= '		<thead>' . PHP_EOL;
                }

                // <tbody> ?
                if ($row == $tbodyStart)
                {
                    $html .= '		<tbody>' . PHP_EOL;
                }

                // Write row if there are HTML table cells in it
                if (!isset($this->_isSpannedRow[$sheet->getParent()->getIndex($sheet)][$row]))
                {
                    // Start a new rowData
                    $rowData = array();
                    // Loop through columns
                    $column  = $dimension[0][0] - 1;
                    while ($column++ < $dimension[1][0])
                    {
                        // Cell exists?
                        if ($sheet->cellExistsByColumnAndRow($column, $row))
                        {
                            $rowData[$column] = $sheet->getCellByColumnAndRow($column, $row);
                        }
                        else
                        {
                            $rowData[$column] = '';
                        }
                    }
                    $html .= $this->_generateRow($sheet, $rowData, $row - 1);
                }

                // </thead> ?
                if ($row == $theadEnd)
                {
                    $html .= '		</thead>' . PHP_EOL;
                }
            }
            $html .= $this->_extendRowsForChartsAndImages($sheet, $row);

            // Close table body.
            $html .= '		</tbody>' . PHP_EOL;

            // Write table footer
            $html .= $this->_generateTableFooter();

            // Writing PDF?
            if ($this->_isPdf)
            {
                if (is_null($this->_sheetIndex) && $sheetId + 1 < $this->_phpExcel->getSheetCount())
                {
                    $html .= '<div style="page-break-before:always" />';
                }
            }

            // Next sheet
            ++$sheetId;
        }

        // Return
        return $html;
    }

    /**
     * Generate sheet tabs
     *
     * @return	string
     * @throws PHPExcel_Writer_Exception
     */
    public function generateNavigation()
    {
        // PHPExcel object known?
        if (is_null($this->_phpExcel))
        {
            throw new PHPExcel_Writer_Exception('Internal PHPExcel object not set to an instance of an object.');
        }

        // Fetch sheets
        $sheets = array();
        if (is_null($this->_sheetIndex))
        {
            $sheets = $this->_phpExcel->getAllSheets();
        }
        else
        {
            $sheets[] = $this->_phpExcel->getSheet($this->_sheetIndex);
        }

        // Construct HTML
        $html = '';

        // Only if there are more than 1 sheets
        if (count($sheets) > 1)
        {
            // Loop all sheets
            $sheetId = 0;

            $html .= '<ul class="navigation">' . PHP_EOL;

            foreach ($sheets as $sheet)
            {
                $html .= '  <li class="sheet' . $sheetId . '"><a href="#sheet' . $sheetId . '">' . $sheet->getTitle() . '</a></li>' . PHP_EOL;
                ++$sheetId;
            }

            $html .= '</ul>' . PHP_EOL;
        }

        return $html;
    }

    private function _extendRowsForChartsAndImages(PHPExcel_Worksheet $pSheet, $row)
    {
        $rowMax = $row;
        $colMax = 'A';
        if ($this->_includeCharts)
        {
            foreach ($pSheet->getChartCollection() as $chart)
            {
                if ($chart instanceof PHPExcel_Chart)
                {
                    $chartCoordinates = $chart->getTopLeftPosition();
                    $chartTL          = PHPExcel_Cell::coordinateFromString($chartCoordinates['cell']);
                    $chartCol         = PHPExcel_Cell::columnIndexFromString($chartTL[0]);
                    if ($chartTL[1] > $rowMax)
                    {
                        $rowMax = $chartTL[1];
                        if ($chartCol > PHPExcel_Cell::columnIndexFromString($colMax))
                        {
                            $colMax = $chartTL[0];
                        }
                    }
                }
            }
        }

        foreach ($pSheet->getDrawingCollection() as $drawing)
        {
            if ($drawing instanceof PHPExcel_Worksheet_Drawing)
            {
                $imageTL  = PHPExcel_Cell::coordinateFromString($drawing->getCoordinates());
                $imageCol = PHPExcel_Cell::columnIndexFromString($imageTL[0]);
                if ($imageTL[1] > $rowMax)
                {
                    $rowMax = $imageTL[1];
                    if ($imageCol > PHPExcel_Cell::columnIndexFromString($colMax))
                    {
                        $colMax = $imageTL[0];
                    }
                }
            }
        }
        $html = '';
        $colMax++;
        while ($row < $rowMax)
        {
            $html .= '<tr>';
            for ($col = 'A'; $col != $colMax; ++$col)
            {
                $html .= '<td>';
                $html .= $this->_writeImageInCell($pSheet, $col . $row);
                if ($this->_includeCharts)
                {
                    $html .= $this->_writeChartInCell($pSheet, $col . $row);
                }
                $html .= '</td>';
            }
            ++$row;
            $html .= '</tr>';
        }
        return $html;
    }

    /**
     * Generate image tag in cell
     *
     * @param	PHPExcel_Worksheet	$pSheet			PHPExcel_Worksheet
     * @param	string				$coordinates	Cell coordinates
     * @return	string
     * @throws	PHPExcel_Writer_Exception
     */
    private function _writeImageInCell(PHPExcel_Worksheet $pSheet, $coordinates)
    {
        // Construct HTML
        $html = '';

        // Write images
        foreach ($pSheet->getDrawingCollection() as $drawing)
        {
            if ($drawing instanceof PHPExcel_Worksheet_Drawing)
            {
                if ($drawing->getCoordinates() == $coordinates)
                {
                    $filename = $drawing->getPath();

                    // Strip off eventual '.'
                    if (substr($filename, 0, 1) == '.')
                    {
                        $filename = substr($filename, 1);
                    }

                    // Prepend images root
                    $filename = $this->getImagesRoot() . $filename;

                    // Strip off eventual '.'
                    if (substr($filename, 0, 1) == '.' && substr($filename, 0, 2) != './')
                    {
                        $filename = substr($filename, 1);
                    }

                    // Convert UTF8 data to PCDATA
                    $filename = htmlspecialchars($filename);

                    $html .= PHP_EOL;
                    if ((!$this->_embedImages) || ($this->_isPdf))
                    {
                        $imageData = $filename;
                    }
                    else
                    {
                        $imageDetails = getimagesize($filename);
                        if ($fp           = fopen($filename, "rb", 0))
                        {
                            $picture   = fread($fp, filesize($filename));
                            fclose($fp);
                            // base64 encode the binary data, then break it
                            // into chunks according to RFC 2045 semantics
                            $base64    = chunk_split(base64_encode($picture));
                            $imageData = 'data:' . $imageDetails['mime'] . ';base64,' . $base64;
                        }
                        else
                        {
                            $imageData = $filename;
                        }
                    }

                    $html .= '<div style="position: relative;">';
                    $html .= '<img style="position: absolute; z-index: 1; left: ' . $drawing->getOffsetX() . 'px; top: ' . $drawing->getOffsetY() . 'px; width: ' . $drawing->getWidth() . 'px; height: ' . $drawing->getHeight() . 'px;" src="' . $imageData . '" border="0" />' . PHP_EOL;
                    $html .= '</div>';
                }
            }
        }

        // Return
        return $html;
    }

    /**
     * Generate chart tag in cell
     *
     * @param	PHPExcel_Worksheet	$pSheet			PHPExcel_Worksheet
     * @param	string				$coordinates	Cell coordinates
     * @return	string
     * @throws	PHPExcel_Writer_Exception
     */
    private function _writeChartInCell(PHPExcel_Worksheet $pSheet, $coordinates)
    {
        // Construct HTML
        $html = '';

        // Write charts
        foreach ($pSheet->getChartCollection() as $chart)
        {
            if ($chart instanceof PHPExcel_Chart)
            {
                $chartCoordinates = $chart->getTopLeftPosition();
                if ($chartCoordinates['cell'] == $coordinates)
                {
                    $chartFileName = PHPExcel_Shared_File::sys_get_temp_dir() . '/' . uniqid() . '.png';
                    if (!$chart->render($chartFileName))
                    {
                        return;
                    }

                    $html .= PHP_EOL;
                    $imageDetails = getimagesize($chartFileName);
                    if ($fp           = fopen($chartFileName, "rb", 0))
                    {
                        $picture   = fread($fp, filesize($chartFileName));
                        fclose($fp);
                        // base64 encode the binary data, then break it
                        // into chunks according to RFC 2045 semantics
                        $base64    = chunk_split(base64_encode($picture));
                        $imageData = 'data:' . $imageDetails['mime'] . ';base64,' . $base64;

                        $html .= '<div style="position: relative;">';
                        $html .= '<img style="position: absolute; z-index: 1; left: ' . $chartCoordinates['xOffset'] . 'px; top: ' . $chartCoordinates['yOffset'] . 'px; width: ' . $imageDetails[0] . 'px; height: ' . $imageDetails[1] . 'px;" src="' . $imageData . '" border="0" />' . PHP_EOL;
                        $html .= '</div>';

                        unlink($chartFileName);
                    }
                }
            }
        }

        // Return
        return $html;
    }

    /**
     * Generate CSS styles
     *
     * @param	boolean	$generateSurroundingHTML	Generate surrounding HTML tags? (<style> and </style>)
     * @return	string
     * @throws	PHPExcel_Writer_Exception
     */
    public function generateStyles($generateSurroundingHTML = true)
    {
        // PHPExcel object known?
        if (is_null($this->_phpExcel))
        {
            throw new PHPExcel_Writer_Exception('Internal PHPExcel object not set to an instance of an object.');
        }

        // Build CSS
        $css = $this->buildCSS($generateSurroundingHTML);

        // Construct HTML
        $html = '';

        // Start styles
        if ($generateSurroundingHTML)
        {
            $html .= '	<style type="text/css">' . PHP_EOL;
            $html .= '	  html { ' . $this->_assembleCSS($css['html']) . ' }' . PHP_EOL;
        }

        // Write all other styles
        foreach ($css as $styleName => $styleDefinition)
        {
            if ($styleName != 'html')
            {
                $html .= '	  ' . $styleName . ' { ' . $this->_assembleCSS($styleDefinition) . ' }' . PHP_EOL;
            }
        }

        // End styles
        if ($generateSurroundingHTML)
        {
            $html .= '	</style>' . PHP_EOL;
        }

        // Return
        return $html;
    }

    /**
     * Build CSS styles
     *
     * @param	boolean	$generateSurroundingHTML	Generate surrounding HTML style? (html { })
     * @return	array
     * @throws	PHPExcel_Writer_Exception
     */
    public function buildCSS($generateSurroundingHTML = true)
    {
        // PHPExcel object known?
        if (is_null($this->_phpExcel))
        {
            throw new PHPExcel_Writer_Exception('Internal PHPExcel object not set to an instance of an object.');
        }

        // Cached?
        if (!is_null($this->_cssStyles))
        {
            return $this->_cssStyles;
        }

        // Ensure that spans have been calculated
        if (!$this->_spansAreCalculated)
        {
            $this->_calculateSpans();
        }

        // Construct CSS
        $css = array();

        // Start styles
        if ($generateSurroundingHTML)
        {
            // html { }
            $css['html']['font-family']      = 'Calibri, Arial, Helvetica, sans-serif';
            $css['html']['font-size']        = '11pt';
            $css['html']['background-color'] = 'white';
        }


        // table { }
        $css['table']['border-collapse'] = 'collapse';
        if (!$this->_isPdf)
        {
            $css['table']['page-break-after'] = 'always';
        }

        // .gridlines td { }
        $css['.gridlines td']['border'] = '1px dotted black';

        // .b {}
        $css['.b']['text-align']         = 'center'; // BOOL
        // .e {}
        $css['.e']['text-align']         = 'center'; // ERROR
        // .f {}
        $css['.f']['text-align']         = 'right'; // FORMULA
        // .inlineStr {}
        $css['.inlineStr']['text-align'] = 'left'; // INLINE
        // .n {}
        $css['.n']['text-align']         = 'right'; // NUMERIC
        // .s {}
        $css['.s']['text-align']         = 'left'; // STRING
        // Calculate cell style hashes
        foreach ($this->_phpExcel->getCellXfCollection() as $index => $style)
        {
            $css['td.style' . $index] = $this->_createCSSStyle($style);
        }

        // Fetch sheets
        $sheets = array();
        if (is_null($this->_sheetIndex))
        {
            $sheets = $this->_phpExcel->getAllSheets();
        }
        else
        {
            $sheets[] = $this->_phpExcel->getSheet($this->_sheetIndex);
        }

        // Build styles per sheet
        foreach ($sheets as $sheet)
        {
            // Calculate hash code
            $sheetIndex = $sheet->getParent()->getIndex($sheet);

            // Build styles
            // Calculate column widths
            $sheet->calculateColumnWidths();

            // col elements, initialize
            $highestColumnIndex = PHPExcel_Cell::columnIndexFromString($sheet->getHighestColumn()) - 1;
            $column             = -1;
            while ($column++ < $highestColumnIndex)
            {
                $this->_columnWidths[$sheetIndex][$column]                        = 42; // approximation
                $css['table.sheet' . $sheetIndex . ' col.col' . $column]['width'] = '42pt';
            }

            // col elements, loop through columnDimensions and set width
            foreach ($sheet->getColumnDimensions() as $columnDimension)
            {
                if (($width = PHPExcel_Shared_Drawing::cellDimensionToPixels($columnDimension->getWidth(), $this->_defaultFont)) >= 0)
                {
                    $width                                                            = PHPExcel_Shared_Drawing::pixelsToPoints($width);
                    $column                                                           = PHPExcel_Cell::columnIndexFromString($columnDimension->getColumnIndex()) - 1;
                    $this->_columnWidths[$sheetIndex][$column]                        = $width;
                    $css['table.sheet' . $sheetIndex . ' col.col' . $column]['width'] = $width . 'pt';

                    if ($columnDimension->getVisible() === false)
                    {
                        $css['table.sheet' . $sheetIndex . ' col.col' . $column]['visibility'] = 'collapse';
                        $css['table.sheet' . $sheetIndex . ' col.col' . $column]['*display']   = 'none'; // target IE6+7
                    }
                }
            }

            // Default row height
            $rowDimension = $sheet->getDefaultRowDimension();

            // table.sheetN tr { }
            $css['table.sheet' . $sheetIndex . ' tr'] = array();

            if ($rowDimension->getRowHeight() == -1)
            {
                $pt_height = PHPExcel_Shared_Font::getDefaultRowHeightByFont($this->_phpExcel->getDefaultStyle()->getFont());
            }
            else
            {
                $pt_height = $rowDimension->getRowHeight();
            }
            $css['table.sheet' . $sheetIndex . ' tr']['height'] = $pt_height . 'pt';
            if ($rowDimension->getVisible() === false)
            {
                $css['table.sheet' . $sheetIndex . ' tr']['display']    = 'none';
                $css['table.sheet' . $sheetIndex . ' tr']['visibility'] = 'hidden';
            }

            // Calculate row heights
            foreach ($sheet->getRowDimensions() as $rowDimension)
            {
                $row = $rowDimension->getRowIndex() - 1;

                // table.sheetN tr.rowYYYYYY { }
                $css['table.sheet' . $sheetIndex . ' tr.row' . $row] = array();

                if ($rowDimension->getRowHeight() == -1)
                {
                    $pt_height = PHPExcel_Shared_Font::getDefaultRowHeightByFont($this->_phpExcel->getDefaultStyle()->getFont());
                }
                else
                {
                    $pt_height = $rowDimension->getRowHeight();
                }
                $css['table.sheet' . $sheetIndex . ' tr.row' . $row]['height'] = $pt_height . 'pt';
                if ($rowDimension->getVisible() === false)
                {
                    $css['table.sheet' . $sheetIndex . ' tr.row' . $row]['display']    = 'none';
                    $css['table.sheet' . $sheetIndex . ' tr.row' . $row]['visibility'] = 'hidden';
                }
            }
        }

        // Cache
        if (is_null($this->_cssStyles))
        {
            $this->_cssStyles = $css;
        }

        // Return
        return $css;
    }

    /**
     * Create CSS style
     *
     * @param	PHPExcel_Style		$pStyle			PHPExcel_Style
     * @return	array
     */
    private function _createCSSStyle(PHPExcel_Style $pStyle)
    {
        // Construct CSS
        $css = '';

        // Create CSS
        $css = array_merge(
                $this->_createCSSStyleAlignment($pStyle->getAlignment())
                , $this->_createCSSStyleBorders($pStyle->getBorders())
                , $this->_createCSSStyleFont($pStyle->getFont())
                , $this->_createCSSStyleFill($pStyle->getFill())
        );

        // Return
        return $css;
    }

    /**
     * Create CSS style (PHPExcel_Style_Alignment)
     *
     * @param	PHPExcel_Style_Alignment		$pStyle			PHPExcel_Style_Alignment
     * @return	array
     */
    private function _createCSSStyleAlignment(PHPExcel_Style_Alignment $pStyle)
    {
        // Construct CSS
        $css = array();

        // Create CSS
        $css['vertical-align'] = $this->_mapVAlign($pStyle->getVertical());
        if ($textAlign             = $this->_mapHAlign($pStyle->getHorizontal()))
        {
            $css['text-align']            = $textAlign;
            if (in_array($textAlign, array('left', 'right')))
                $css['padding-' . $textAlign] = (string) ((int) $pStyle->getIndent() * 9) . 'px';
        }

        // Return
        return $css;
    }

    /**
     * Create CSS style (PHPExcel_Style_Font)
     *
     * @param	PHPExcel_Style_Font		$pStyle			PHPExcel_Style_Font
     * @return	array
     */
    private function _createCSSStyleFont(PHPExcel_Style_Font $pStyle)
    {
        // Construct CSS
        $css = array();

        // Create CSS
        if ($pStyle->getBold())
        {
            $css['font-weight'] = 'bold';
        }
        if ($pStyle->getUnderline() != PHPExcel_Style_Font::UNDERLINE_NONE && $pStyle->getStrikethrough())
        {
            $css['text-decoration'] = 'underline line-through';
        }
        else if ($pStyle->getUnderline() != PHPExcel_Style_Font::UNDERLINE_NONE)
        {
            $css['text-decoration'] = 'underline';
        }
        else if ($pStyle->getStrikethrough())
        {
            $css['text-decoration'] = 'line-through';
        }
        if ($pStyle->getItalic())
        {
            $css['font-style'] = 'italic';
        }

        $css['color']       = '#' . $pStyle->getColor()->getRGB();
        $css['font-family'] = '\'' . $pStyle->getName() . '\'';
        $css['font-size']   = $pStyle->getSize() . 'pt';

        // Return
        return $css;
    }

    /**
     * Create CSS style (PHPExcel_Style_Borders)
     *
     * @param	PHPExcel_Style_Borders		$pStyle			PHPExcel_Style_Borders
     * @return	array
     */
    private function _createCSSStyleBorders(PHPExcel_Style_Borders $pStyle)
    {
        // Construct CSS
        $css = array();

        // Create CSS
        $css['border-bottom'] = $this->_createCSSStyleBorder($pStyle->getBottom());
        $css['border-top']    = $this->_createCSSStyleBorder($pStyle->getTop());
        $css['border-left']   = $this->_createCSSStyleBorder($pStyle->getLeft());
        $css['border-right']  = $this->_createCSSStyleBorder($pStyle->getRight());

        // Return
        return $css;
    }

    /**
     * Create CSS style (PHPExcel_Style_Border)
     *
     * @param	PHPExcel_Style_Border		$pStyle			PHPExcel_Style_Border
     * @return	string
     */
    private function _createCSSStyleBorder(PHPExcel_Style_Border $pStyle)
    {
        // Create CSS
//		$css = $this->_mapBorderStyle($pStyle->getBorderStyle()) . ' #' . $pStyle->getColor()->getRGB();
        //	Create CSS - add !important to non-none border styles for merged cells  
        $borderStyle = $this->_mapBorderStyle($pStyle->getBorderStyle());
        $css         = $borderStyle . ' #' . $pStyle->getColor()->getRGB() . (($borderStyle == 'none') ? '' : ' !important');

        // Return
        return $css;
    }

    /**
     * Create CSS style (PHPExcel_Style_Fill)
     *
     * @param	PHPExcel_Style_Fill		$pStyle			PHPExcel_Style_Fill
     * @return	array
     */
    private function _createCSSStyleFill(PHPExcel_Style_Fill $pStyle)
    {
        // Construct HTML
        $css = array();

        // Create CSS
        $value                   = $pStyle->getFillType() == PHPExcel_Style_Fill::FILL_NONE ?
                'white' : '#' . $pStyle->getStartColor()->getRGB();
        $css['background-color'] = $value;

        // Return
        return $css;
    }

    /**
     * Generate HTML footer
     */
    public function generateHTMLFooter()
    {
        // Construct HTML
        $html = '';
        $html .= '  </body>' . PHP_EOL;
        $html .= '</html>' . PHP_EOL;

        // Return
        return $html;
    }

    /**
     * Generate table header
     *
     * @param	PHPExcel_Worksheet	$pSheet		The worksheet for the table we are writing
     * @return	string
     * @throws	PHPExcel_Writer_Exception
     */
    private function _generateTableHeader($pSheet)
    {
        $sheetIndex = $pSheet->getParent()->getIndex($pSheet);

        // Construct HTML
        $html = '';
        $html .= $this->_setMargins($pSheet);

        if (!$this->_useInlineCss)
        {
            $gridlines = $pSheet->getShowGridLines() ? ' gridlines' : '';
            $html .= '	<table border="0" cellpadding="0" cellspacing="0" id="sheet' . $sheetIndex . '" class="sheet' . $sheetIndex . $gridlines . '">' . PHP_EOL;
        }
        else
        {
            $style = isset($this->_cssStyles['table']) ?
                    $this->_assembleCSS($this->_cssStyles['table']) : '';

            if ($this->_isPdf && $pSheet->getShowGridLines())
            {
                $html .= '	<table border="1" cellpadding="1" id="sheet' . $sheetIndex . '" cellspacing="1" style="' . $style . '">' . PHP_EOL;
            }
            else
            {
                $html .= '	<table border="0" cellpadding="1" id="sheet' . $sheetIndex . '" cellspacing="0" style="' . $style . '">' . PHP_EOL;
            }
        }

        // Write <col> elements
        $highestColumnIndex = PHPExcel_Cell::columnIndexFromString($pSheet->getHighestColumn()) - 1;
        $i                  = -1;
        while ($i++ < $highestColumnIndex)
        {
            if (!$this->_isPdf)
            {
                if (!$this->_useInlineCss)
                {
                    $html .= '		<col class="col' . $i . '">' . PHP_EOL;
                }
                else
                {
                    $style = isset($this->_cssStyles['table.sheet' . $sheetIndex . ' col.col' . $i]) ?
                            $this->_assembleCSS($this->_cssStyles['table.sheet' . $sheetIndex . ' col.col' . $i]) : '';
                    $html .= '		<col style="' . $style . '">' . PHP_EOL;
                }
            }
        }

        // Return
        return $html;
    }

    /**
     * Generate table footer
     *
     * @throws	PHPExcel_Writer_Exception
     */
    private function _generateTableFooter()
    {
        // Construct HTML
        $html = '';
        $html .= '	</table>' . PHP_EOL;

        // Return
        return $html;
    }

    /**
     * Generate row
     *
     * @param	PHPExcel_Worksheet	$pSheet			PHPExcel_Worksheet
     * @param	array				$pValues		Array containing cells in a row
     * @param	int					$pRow			Row number (0-based)
     * @return	string
     * @throws	PHPExcel_Writer_Exception
     */
    private function _generateRow(PHPExcel_Worksheet $pSheet, $pValues = null, $pRow = 0)
    {
        if (is_array($pValues))
        {
            // Construct HTML
            $html = '';

            // Sheet index
            $sheetIndex = $pSheet->getParent()->getIndex($pSheet);

            // DomPDF and breaks
            if ($this->_isPdf && count($pSheet->getBreaks()) > 0)
            {
                $breaks = $pSheet->getBreaks();

                // check if a break is needed before this row
                if (isset($breaks['A' . $pRow]))
                {
                    // close table: </table>
                    $html .= $this->_generateTableFooter();

                    // insert page break
                    $html .= '<div style="page-break-before:always" />';

                    // open table again: <table> + <col> etc.
                    $html .= $this->_generateTableHeader($pSheet);
                }
            }

            // Write row start
            if (!$this->_useInlineCss)
            {
                $html .= '		  <tr class="row' . $pRow . '">' . PHP_EOL;
            }
            else
            {
                $style = isset($this->_cssStyles['table.sheet' . $sheetIndex . ' tr.row' . $pRow]) ? $this->_assembleCSS($this->_cssStyles['table.sheet' . $sheetIndex . ' tr.row' . $pRow]) : '';

                $html .= '		  <tr style="' . $style . '">' . PHP_EOL;
            }

            // Write cells
            $colNum = 0;
            foreach ($pValues as $cell)
            {
                $coordinate = PHPExcel_Cell::stringFromColumnIndex($colNum) . ($pRow + 1);

                if (!$this->_useInlineCss)
                {
                    $cssClass = '';
                    $cssClass = 'column' . $colNum;
                }
                else
                {
                    $cssClass = array();
                    if (isset($this->_cssStyles['table.sheet' . $sheetIndex . ' td.column' . $colNum]))
                    {
                        $this->_cssStyles['table.sheet' . $sheetIndex . ' td.column' . $colNum];
                    }
                }
                $colSpan = 1;
                $rowSpan = 1;

                // initialize
                $cellData = '&nbsp;';

                // PHPExcel_Cell
                if ($cell instanceof PHPExcel_Cell)
                {
                    $cellData = '';
                    if (is_null($cell->getParent()))
                    {
                        $cell->attach($pSheet);
                    }
                    // Value
                    if ($cell->getValue() instanceof PHPExcel_RichText)
                    {
                        // Loop through rich text elements
                        $elements = $cell->getValue()->getRichTextElements();
                        foreach ($elements as $element)
                        {
                            // Rich text start?
                            if ($element instanceof PHPExcel_RichText_Run)
                            {
                                $cellData .= '<span style="' . $this->_assembleCSS($this->_createCSSStyleFont($element->getFont())) . '">';

                                if ($element->getFont()->getSuperScript())
                                {
                                    $cellData .= '<sup>';
                                }
                                else if ($element->getFont()->getSubScript())
                                {
                                    $cellData .= '<sub>';
                                }
                            }

                            // Convert UTF8 data to PCDATA
                            $cellText = $element->getText();
                            $cellData .= htmlspecialchars($cellText);

                            if ($element instanceof PHPExcel_RichText_Run)
                            {
                                if ($element->getFont()->getSuperScript())
                                {
                                    $cellData .= '</sup>';
                                }
                                else if ($element->getFont()->getSubScript())
                                {
                                    $cellData .= '</sub>';
                                }

                                $cellData .= '</span>';
                            }
                        }
                    }
                    else
                    {
                        if ($this->_preCalculateFormulas)
                        {
                            $cellData = PHPExcel_Style_NumberFormat::toFormattedString(
                                            $cell->getCalculatedValue(), $pSheet->getParent()->getCellXfByIndex($cell->getXfIndex())->getNumberFormat()->getFormatCode(), array($this, 'formatColor')
                            );
                        }
                        else
                        {
                            $cellData = PHPExcel_Style_NumberFormat::ToFormattedString(
                                            $cell->getValue(), $pSheet->getParent()->getCellXfByIndex($cell->getXfIndex())->getNumberFormat()->getFormatCode(), array($this, 'formatColor')
                            );
                        }
                        $cellData = htmlspecialchars($cellData);
                        if ($pSheet->getParent()->getCellXfByIndex($cell->getXfIndex())->getFont()->getSuperScript())
                        {
                            $cellData = '<sup>' . $cellData . '</sup>';
                        }
                        elseif ($pSheet->getParent()->getCellXfByIndex($cell->getXfIndex())->getFont()->getSubScript())
                        {
                            $cellData = '<sub>' . $cellData . '</sub>';
                        }
                    }

                    // Converts the cell content so that spaces occuring at beginning of each new line are replaced by &nbsp;
                    // Example: "  Hello\n to the world" is converted to "&nbsp;&nbsp;Hello\n&nbsp;to the world"
                    $cellData = preg_replace("/(?m)(?:^|\\G) /", '&nbsp;', $cellData);

                    // convert newline "\n" to '<br>'
                    $cellData = nl2br($cellData);

                    // Extend CSS class?
                    if (!$this->_useInlineCss)
                    {
                        $cssClass .= ' style' . $cell->getXfIndex();
                        $cssClass .= ' ' . $cell->getDataType();
                    }
                    else
                    {
                        if (isset($this->_cssStyles['td.style' . $cell->getXfIndex()]))
                        {
                            $cssClass = array_merge($cssClass, $this->_cssStyles['td.style' . $cell->getXfIndex()]);
                        }

                        // General horizontal alignment: Actual horizontal alignment depends on dataType
                        $sharedStyle = $pSheet->getParent()->getCellXfByIndex($cell->getXfIndex());
                        if ($sharedStyle->getAlignment()->getHorizontal() == PHPExcel_Style_Alignment::HORIZONTAL_GENERAL && isset($this->_cssStyles['.' . $cell->getDataType()]['text-align']))
                        {
                            $cssClass['text-align'] = $this->_cssStyles['.' . $cell->getDataType()]['text-align'];
                        }
                    }
                }

                // Hyperlink?
                if ($pSheet->hyperlinkExists($coordinate) && !$pSheet->getHyperlink($coordinate)->isInternal())
                {
                    $cellData = '<a href="' . htmlspecialchars($pSheet->getHyperlink($coordinate)->getUrl()) . '" title="' . htmlspecialchars($pSheet->getHyperlink($coordinate)->getTooltip()) . '">' . $cellData . '</a>';
                }

                // Should the cell be written or is it swallowed by a rowspan or colspan?
                $writeCell = !( isset($this->_isSpannedCell[$pSheet->getParent()->getIndex($pSheet)][$pRow + 1][$colNum]) && $this->_isSpannedCell[$pSheet->getParent()->getIndex($pSheet)][$pRow + 1][$colNum] );

                // Colspan and Rowspan
                $colspan = 1;
                $rowspan = 1;
                if (isset($this->_isBaseCell[$pSheet->getParent()->getIndex($pSheet)][$pRow + 1][$colNum]))
                {
                    $spans   = $this->_isBaseCell[$pSheet->getParent()->getIndex($pSheet)][$pRow + 1][$colNum];
                    $rowSpan = $spans['rowspan'];
                    $colSpan = $spans['colspan'];

                    //	Also apply style from last cell in merge to fix borders -
                    //		relies on !important for non-none border declarations in _createCSSStyleBorder
                    $endCellCoord = PHPExcel_Cell::stringFromColumnIndex($colNum + $colSpan - 1) . ($pRow + $rowSpan);
                    $cssClass .= ' style' . $pSheet->getCell($endCellCoord)->getXfIndex();
                }

                // Write
                if ($writeCell)
                {
                    // Column start
                    $html .= '			<td';
                    if (!$this->_useInlineCss)
                    {
                        $html .= ' class="' . $cssClass . '"';
                    }
                    else
                    {
                        //** Necessary redundant code for the sake of PHPExcel_Writer_PDF **
                        // We must explicitly write the width of the <td> element because TCPDF
                        // does not recognize e.g. <col style="width:42pt">
                        $width = 0;
                        $i     = $colNum - 1;
                        $e     = $colNum + $colSpan - 1;
                        while ($i++ < $e)
                        {
                            if (isset($this->_columnWidths[$sheetIndex][$i]))
                            {
                                $width += $this->_columnWidths[$sheetIndex][$i];
                            }
                        }
                        $cssClass['width'] = $width . 'pt';

                        // We must also explicitly write the height of the <td> element because TCPDF
                        // does not recognize e.g. <tr style="height:50pt">
                        if (isset($this->_cssStyles['table.sheet' . $sheetIndex . ' tr.row' . $pRow]['height']))
                        {
                            $height             = $this->_cssStyles['table.sheet' . $sheetIndex . ' tr.row' . $pRow]['height'];
                            $cssClass['height'] = $height;
                        }
                        //** end of redundant code **

                        $html .= ' style="' . $this->_assembleCSS($cssClass) . '"';
                    }
                    if ($colSpan > 1)
                    {
                        $html .= ' colspan="' . $colSpan . '"';
                    }
                    if ($rowSpan > 1)
                    {
                        $html .= ' rowspan="' . $rowSpan . '"';
                    }
                    $html .= '>';

                    // Image?
                    $html .= $this->_writeImageInCell($pSheet, $coordinate);

                    // Chart?
                    if ($this->_includeCharts)
                    {
                        $html .= $this->_writeChartInCell($pSheet, $coordinate);
                    }

                    // Cell data
                    $html .= $cellData;

                    // Column end
                    $html .= '</td>' . PHP_EOL;
                }

                // Next column
                ++$colNum;
            }

            // Write row end
            $html .= '		  </tr>' . PHP_EOL;

            // Return
            return $html;
        }
        else
        {
            throw new PHPExcel_Writer_Exception("Invalid parameters passed.");
        }
    }

    /**
     * Takes array where of CSS properties / values and converts to CSS string
     *
     * @param array
     * @return string
     */
    private function _assembleCSS($pValue = array())
    {
        $pairs = array();
        foreach ($pValue as $property => $value)
        {
            $pairs[] = $property . ':' . $value;
        }
        $string = implode('; ', $pairs);

        return $string;
    }

    /**
     * Get images root
     *
     * @return string
     */
    public function getImagesRoot()
    {
        return $this->_imagesRoot;
    }

    /**
     * Set images root
     *
     * @param string $pValue
     * @return PHPExcel_Writer_HTML
     */
    public function setImagesRoot($pValue = '.')
    {
        $this->_imagesRoot = $pValue;
        return $this;
    }

    /**
     * Get embed images
     *
     * @return boolean
     */
    public function getEmbedImages()
    {
        return $this->_embedImages;
    }

    /**
     * Set embed images
     *
     * @param boolean $pValue
     * @return PHPExcel_Writer_HTML
     */
    public function setEmbedImages($pValue = '.')
    {
        $this->_embedImages = $pValue;
        return $this;
    }

    /**
     * Get use inline CSS?
     *
     * @return boolean
     */
    public function getUseInlineCss()
    {
        return $this->_useInlineCss;
    }

    /**
     * Set use inline CSS?
     *
     * @param boolean $pValue
     * @return PHPExcel_Writer_HTML
     */
    public function setUseInlineCss($pValue = false)
    {
        $this->_useInlineCss = $pValue;
        return $this;
    }

    /**
     * Add color to formatted string as inline style
     *
     * @param string $pValue Plain formatted value without color
     * @param string $pFormat Format code
     * @return string
     */
    public function formatColor($pValue, $pFormat)
    {
        // Color information, e.g. [Red] is always at the beginning
        $color   = null; // initialize
        $matches = array();

        $color_regex = '/^\\[[a-zA-Z]+\\]/';
        if (preg_match($color_regex, $pFormat, $matches))
        {
            $color = str_replace('[', '', $matches[0]);
            $color = str_replace(']', '', $color);
            $color = strtolower($color);
        }

        // convert to PCDATA
        $value = htmlspecialchars($pValue);

        // color span tag
        if ($color !== null)
        {
            $value = '<span style="color:' . $color . '">' . $value . '</span>';
        }

        return $value;
    }

    /**
     * Calculate information about HTML colspan and rowspan which is not always the same as Excel's
     */
    private function _calculateSpans()
    {
        // Identify all cells that should be omitted in HTML due to cell merge.
        // In HTML only the upper-left cell should be written and it should have
        //   appropriate rowspan / colspan attribute
        $sheetIndexes = $this->_sheetIndex !== null ?
                array($this->_sheetIndex) : range(0, $this->_phpExcel->getSheetCount() - 1);

        foreach ($sheetIndexes as $sheetIndex)
        {
            $sheet = $this->_phpExcel->getSheet($sheetIndex);

            $candidateSpannedRow = array();

            // loop through all Excel merged cells
            foreach ($sheet->getMergeCells() as $cells)
            {
                list($cells, ) = PHPExcel_Cell::splitRange($cells);
                $first = $cells[0];
                $last  = $cells[1];

                list($fc, $fr) = PHPExcel_Cell::coordinateFromString($first);
                $fc = PHPExcel_Cell::columnIndexFromString($fc) - 1;

                list($lc, $lr) = PHPExcel_Cell::coordinateFromString($last);
                $lc = PHPExcel_Cell::columnIndexFromString($lc) - 1;

                // loop through the individual cells in the individual merge
                $r = $fr - 1;
                while ($r++ < $lr)
                {
                    // also, flag this row as a HTML row that is candidate to be omitted
                    $candidateSpannedRow[$r] = $r;

                    $c = $fc - 1;
                    while ($c++ < $lc)
                    {
                        if (!($c == $fc && $r == $fr))
                        {
                            // not the upper-left cell (should not be written in HTML)
                            $this->_isSpannedCell[$sheetIndex][$r][$c] = array(
                                'baseCell' => array($fr, $fc),
                            );
                        }
                        else
                        {
                            // upper-left is the base cell that should hold the colspan/rowspan attribute
                            $this->_isBaseCell[$sheetIndex][$r][$c] = array(
                                'xlrowspan' => $lr - $fr + 1, // Excel rowspan
                                'rowspan'   => $lr - $fr + 1, // HTML rowspan, value may change
                                'xlcolspan' => $lc - $fc + 1, // Excel colspan
                                'colspan'   => $lc - $fc + 1, // HTML colspan, value may change
                            );
                        }
                    }
                }
            }

            // Identify which rows should be omitted in HTML. These are the rows where all the cells
            //   participate in a merge and the where base cells are somewhere above.
            $countColumns = PHPExcel_Cell::columnIndexFromString($sheet->getHighestColumn());
            foreach ($candidateSpannedRow as $rowIndex)
            {
                if (isset($this->_isSpannedCell[$sheetIndex][$rowIndex]))
                {
                    if (count($this->_isSpannedCell[$sheetIndex][$rowIndex]) == $countColumns)
                    {
                        $this->_isSpannedRow[$sheetIndex][$rowIndex] = $rowIndex;
                    };
                }
            }

            // For each of the omitted rows we found above, the affected rowspans should be subtracted by 1
            if (isset($this->_isSpannedRow[$sheetIndex]))
            {
                foreach ($this->_isSpannedRow[$sheetIndex] as $rowIndex)
                {
                    $adjustedBaseCells = array();
                    $c                 = -1;
                    $e                 = $countColumns - 1;
                    while ($c++ < $e)
                    {
                        $baseCell = $this->_isSpannedCell[$sheetIndex][$rowIndex][$c]['baseCell'];

                        if (!in_array($baseCell, $adjustedBaseCells))
                        {
                            // subtract rowspan by 1
                            --$this->_isBaseCell[$sheetIndex][$baseCell[0]][$baseCell[1]]['rowspan'];
                            $adjustedBaseCells[] = $baseCell;
                        }
                    }
                }
            }

            // TODO: Same for columns
        }

        // We have calculated the spans
        $this->_spansAreCalculated = true;
    }

    private function _setMargins(PHPExcel_Worksheet $pSheet)
    {
        $htmlPage = '@page { ';
        $htmlBody = 'body { ';

        $left   = PHPExcel_Shared_String::FormatNumber($pSheet->getPageMargins()->getLeft()) . 'in; ';
        $htmlPage .= 'left-margin: ' . $left;
        $htmlBody .= 'left-margin: ' . $left;
        $right  = PHPExcel_Shared_String::FormatNumber($pSheet->getPageMargins()->getRight()) . 'in; ';
        $htmlPage .= 'right-margin: ' . $right;
        $htmlBody .= 'right-margin: ' . $right;
        $top    = PHPExcel_Shared_String::FormatNumber($pSheet->getPageMargins()->getTop()) . 'in; ';
        $htmlPage .= 'top-margin: ' . $top;
        $htmlBody .= 'top-margin: ' . $top;
        $bottom = PHPExcel_Shared_String::FormatNumber($pSheet->getPageMargins()->getBottom()) . 'in; ';
        $htmlPage .= 'bottom-margin: ' . $bottom;
        $htmlBody .= 'bottom-margin: ' . $bottom;

        $htmlPage .= "}\n";
        $htmlBody .= "}\n";

        return "<style>\n" . $htmlPage . $htmlBody . "</style>\n";
    }

}
